Improvement of memory properties for MANOS-type nonvolatile memory devices with high-pressure wet vapor annealing

Effects of high-pressure wet vapor annealing (HPWA) on the memory properties of Metal/Alumina/Nitride/Oxide/Silicon (MANOS)-type flash memory devices are studied. The Oxide/Nitride/Alumina (ONA) stacks were annealed in a high-pressure wet vapor ambient (N2:D2O = 10 atm:2 atm) at 250 °C for 5 min. It is found that HPWA can effectively passivate the intrinsic defects of the Al2O3 film by oxygen species, leading to the improvement of blocking efficiency. The HPWA significantly improved the electrical and reliability characteristics of ONA stacks, such as leakage current density, saturation level of erase, charge loss rate through the blocking oxide, and memory window after the program and erase cycles. HPWA shows promise for future MANOS-type flash memory devices.